Random scale and rotation within range and in circular shape (tree leaves)
Your question lack precisions, but here is a try:

Create your leaf object, here I've used a PNG picture with a transparent background. The following setup is very basic: it would need a bit of glossiness and translucency, and maybe random colors variations:



Create the emitter. Here, to stick to the way the leaves emit, I've created a series of cylinders and cones:



Give your object a Particle System. Choose Hair, enable Advanced, in Emission choose the Number of leaves you want to emit, enable Rotation, in Render choose Render As &gt; Object, disable the Show Emitter option, and in Instance Object choose the leaf. Tweak with the various Rotation and Scale values.



Your bush of leaves should show: